Optical fibers are used ubiquitously in lighting and imaging applications, as well as in the telecommunication industry, where they provide higher data transmission rates over longer distances as compared to electric wiring. In addition, optical fibers are more flexible, lighter, and can be drawn into thinner diameters than metal wiring, allowing for higher-capacity bundling of fibers into cables. Surface coatings, applied via an ultra-violet (UV) curing process, are employed to protect optical fibers from physical damage and moisture intrusion, and to maintain their long-term durability in performance.
Carter et al. (U.S. Pat. No. 6,626,561) addresses UV curing uniformity issues for optical fibers having surfaces that are located outside a focal point of a UV curing device employing an elliptical reflector to direct UV light from a single UV light source positioned at a second focal point of the elliptical reflector, to the surface of the optical fiber. Curing uniformity issues can arise due to imprecise alignment of the optical fiber relative to the light source, or an irregular-shaped optical fiber. To address these issues, Carter uses a UV lamp structure employing an elliptical reflector to irradiate optical fiber surfaces positioned in the vicinity of a second elliptical reflector focal point with UV light from a single light source positioned in the vicinity of a first elliptical reflector focal point, wherein both the optical fiber and bulb are displaced slightly from the focal points. In this manner, the UV light rays reaching the surface of the optical fiber are dispersed, and the irradiation and curing of the optical coating can potentially be more uniform.
The inventor herein has recognized a potential issue with the above approach. Namely, by displacing the UV light source and the optical fiber away from the focal points of the elliptical reflector, the intensity of UV light irradiating the optical fiber surfaces is dispersed and reduced, thereby lowering the curing and production rates, and imparting higher manufacturing costs.
One approach that addresses the aforementioned issues includes a UV curing device, comprising one or more LED array light sources including shaped compound parabolic reflectors arranged to be equally spaced around a workpiece, wherein the compound parabolic reflectors are configured to reduce the emitting angle of the light such that a cylindrical lens can focus the light intensely to the workpiece. Each of the one or more LED array light sources comprising a compound parabolic reflector and cylindrical lens may be aligned to have an output focal position near or along a central axis of the workpiece. In this manner, it is possible to irradiate optical fibers or other workpieces with UV light both uniformly and with high intensity, providing rapid and uniform cure of coatings for optical fibers and other workpieces.
It will be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.